1. Field
The following description relates to a semiconductor device, and to a high-voltage lateral MOSFET semiconductor device having an increased breakdown voltage without a separate epitaxial layer or buried layer formed therein and a method of fabricating such a high-voltage lateral MOSFET device.
2. Description of Related Art
In a conventional N-type lateral double diffused metal oxide semiconductor transistor (LDMOS), a body region that includes a source region is connected to a ground power supply. The breakdown voltage from an N+ source region to the body region of the N-type LDMOS is restricted in its range. For instance, the breakdown voltage is restricted to about 20 V or less.
Various methods for increasing the low breakdown voltage of LDMOS devices have been suggested. For example, there have been suggested a method of forming an expanded deep well so as to surround the body region and a method of forming an N-diffusion region so as to surround the N+ source region. It is possible to increase the breakdown voltage by a certain level by applying the above-described methods. However, the range of breakdown voltage achieved does not reach approximately 100 V or greater. Further, the cost for producing MOSFET devices is increased with these methods due to the need for additional manufacturing steps.
Further, there has been suggested a method of fully isolating the body region from a substrate by forming a thick epitaxial layer on the substrate and forming a buried layer between the substrate and the deep well region. Unfortunately, a technical configuration in which the buried layer and the thick epitaxial layer are formed is undesirable as a high unit price is needed. Also, there are many applications that do not require the technical configuration in which the body region is fully isolated from the substrate.
Patent Literature 1: Korea Patent Laid-Open Publication No. 10-1998-074299